108 : PLATE XXX. 
OBOLUS SCHMALENSEEI (Walcott) (p. 412). 
Ficure 19. Broad form of the ventral valve, showing cast of pedicle furrow and a portion of the visceral cavity. U.S. 
Nat. Mus. Cat. No. 35291a. 
19a. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 35291b. 
19b. An elongate ventral valve. U.S. Nat. Mus. Cat. No. 35291c. 
19c. Cast of a dorsal valve, showing the strongly marked area and margins of the posterior portion of the visceral 
cavity. U.S. Nat. Mus. Cat. No. 35291d. 
19d. Partly exfoliated ventral and dorsal valves, the type specimen. U.S. Nat. Mus. Cat. No. 35291e. 
19e. A small ventral valve. U.S. Nat. Mus. Cat. No. 35291f. 
The specimens represented are all from Locality 8w, Middle Cambrian limestone at Andrarum, Province of 
Christianstad, Sweden. 
ELKanta IDA (Billings) (p. 563). 
[ PI. LI, figs. 4, 4a-e.] 
Ficure 20. A probable ventral valve, from Locality 319, Lower Ordovician limestone of No. 1 of Billings’s section, Point 
Levis, Quebec, Canada. Geol. Survey Canada. 
20a. Dorsal valve from the locality represented by figure 20. Geol. Survey Canada. 
